Gas sensors are known for determining composition concentrations in hot gases, for example, combustion exhaust gases produced by an internal combustion engine. A typical gas sensor includes a ceramic sensing element which includes electrodes at a sensing end thereof that are exposed to the gas being sensed while an opposing terminal end of the sensing element is fluidly isolated from the sensing end. The sensing element is commonly mounted in a metallic shell, and consequently, the sensing element must be sealed with respect to the shell in order to fluidly isolate the terminal end of the sensing element from the sensing end of the sensing element.
Various arrangements are currently used to seal the sensing element with respect to the shell in order to fluidly isolate the terminal end of the sensing element from the sensing end of the sensing element. In U.S. Pat. No. 5,238,551 to Katsu et al., talc that has been compressed between ceramic supports is used to form this seal. However, such a talc seal may not be effective under all conditions that the gas sensor may experience. In U.S. Pat. No. 6,477,887 to Ozawa et al., the sealing arrangement includes a glass seal which seals between the sensing element and an insulator while a mechanical seal is compressed to seal between the insulator and the shell. While this sealing arrangement may be effective, the mechanical seal requires an additional part which adds cost and complexity to the process.
What is needed is a gas sensor which minimizes or eliminates one or more of the shortcomings as set forth above.